Adenosine A1 agonists for the treatment of glaucoma and ocular hypertension

ABSTRACT

The present invention relates to the use of selective adenosine A 1  agonists, in particular the dicyanopyridines of formula (I), for the treatment and/or prophylaxis of glaucoma and ocular hypertension as well as the their use for the production of a medicament for the treatment and/or prophylaxis of glaucoma and ocular hypertension.

The present invention relates to selective adenosine A1 agonists, in particular the dicyanopyridines of formula (I), for the use in a method for the treatment and/or prophylaxis of glaucoma, normotensive glaucoma, ocular hypertension and/or combinations thereof as well as the their use for the production of a medicament for the treatment and/or prophylaxis of glaucoma, normotensive glaucoma, ocular hypertension and/or combinations thereof.

BACKGROUND OF THE INTERVENTION

Glaucoma is a degenerative disease comprising a group of debilitating eye diseases that are a leading cause of permanent loss of visual function due to irreversible damage to the optical nerve. Glaucoma refers further to a disease of the eye, characterized and caused by damage of the optic nerve head, degeneration of ocular tissues, and/or elevated intraocular pressure. There are several functionally or morphologically distinct types of glaucoma which in general are accompanied by elevated intraocular pressure (IOP).

The increased IOP is considered to be causally related to the pathological progress of the disease. In patients with ocular hypertension intraocular pressure is elevated but no apparent loss of visual function has occurred. These patients are considered to be at high risk for a potential development of visual loss associated with glaucoma. Some patients which show a glaucomatous vision field loss have a normal to low intraocular pressure. These so called normotension or low tension glaucoma patients can also benefit form agents that decrease intraocular pressure. The loss of visual function and the progressive deterioration associated with glaucoma and ocular hypertension can generally be ameliorated with medications that reduce elevated intraocular hypertension when glaucoma or ocular hypertension is detected early.

Glaucoma—on the basis of its etiology—refers also to primary or secondary glaucoma. Primary glaucoma in adults (congenital glaucoma) may be either open-angle or acute or chronic angle-closure.

Primary glaucoma is characterized by increased intraocular tension which is due to the obstruction of aqueous humor outflow. In chronic open-angle glaucoma (POAG), the anterior chamber and its anatomic structures appear normal, but drainage of the aqueous humor is hampered. In acute or chronic angle-closure, the filtration angle is narrowed, the anterior chamber is shallow and the iris may obstruct the trabecular meshwork at the entrance of the canal of Schlemm. Dilation of the pupil may push the root of the iris forward against the angle, and may produce pupilary block and thus precipitate an acute attack. A predisposion to acute angle—closure glaucoma attacks with various degrees of severity is know in patients eyes with narrow anterior chamber angles

Secondary glaucoma is characterized and caused by any interference which effects the flow of aqueous humor from the posterior chamber into the anterior chamber and subsequently, into the canal of Schlemm. Also inflammatory disease of the anterior segment may inhibit aqueous outflow by causing complete posterior synechia in iris bombe and may plug the drainage channel with exudates. Other common causes are intraocular tumors, enlarged cataracts, central retinal vein occlusion, trauma to the eye, operative procedures and intraocular hemorrhage.

Several therapies for treating glaucoma or ocular hypertension have been proven to be effective in clinical practice via reduction of IOP by lowering aqueous humor production or by increasing outflow facility. Many of the used drugs are administrated topically direct to the eye or orally. However a relevant amount of patients do not respond to the current existing glaucoma treatment options. In addition a significant amount of patients face side effects like local intolerance and allergic reactions, subconjunctival hyperemia, miosis or uveitis which lead to cessation of the glaucoma therapy. Therefore the need of new and innovative therapeutic agents which control IOP is given. Since glaucoma is caused by progressive damage to the optic nerve head in particular additional neuroprotective effects in the eye would be beneficial.

Thus intense research efforts are currently ongoing for new glaucoma therapies with improved efficacy and reduced side effect profile.

Adenosine, a purine nucleoside, is an ubiquitous modulator of numerous physiological activities which is mediated by specific cell surface receptors. Adenosine is formed intracellularly as an intermediate during the degradation of adenosine 5′-monophosphate (AMP) and S-adenosylhomocysteine, but it can be released from the cell, in which case it acts as a hormone-like substance or neurotransmitter by binding to specific receptors.

The first identified biological action of adenosine was the effect on heart rate, atrioventricular conduction and blood pressure (Lit. 1). Since then it has been reported that adenosine is involved in many physiological processes and that these effects are mainly mediated by four known subtypes of adenosine receptors—referred to as A1, A2a, A2b and A3—each of which has a unique pharmacological profile, tissue distribution and effector coupling (Lit. 2). According to the invention, “adenosine-receptor-selective ligands” are substances which bind selectively to one or more subtypes of the adenosine receptors, thus either mimicking the action of adenosine (adenosine agonists) or blocking its action (adenosine antagonists).

The actions of these adenosine receptors are mediated intracellularly by the messenger cAMP. In the case of the binding of adenosine to the A2a or A2b receptors, the intracellular cAMP is increased via activation of the membrane-bound adenylate cyclase, whereas binding of adenosine to the A1 or A3 receptors results in a decrease of the intracellular cAMP concentration via inhibition of adenylate cyclase.

In the cardiovascular system, the main consequences of the activation of adenosine receptors are: bradycardia, negative inotropism and protection of the heart against ischemia (“preconditioning”) via A1 receptors, dilation of the blood vessels via A2a and A2b receptors and inhibition of the fibroblasts and smooth-muscle-cell proliferation via A2b receptors. In the case of A1 agonists (coupling preferably via G, proteins), a decrease of the intracellular cAMP concentration is observed (preferably after direct prestimulation of adenylate cyclase by forskolin). Correspondingly, A2a and A2b agonists (coupling preferably via G, proteins) leads to an increase and A2a and A2b antagonists to a decrease of the cAMP concentration in the cells. In the case of A2 receptors, a direct prestimulation of adenylate cyclase by forskolin is of no benefit.

The development of many subtype specific adenosine receptor agonists or antagonists have been described and tested in clinical trails for many different diseases e.g. cardiac arrhythmias, neuropathic pain, myocardial perfusion imaging, inflammatory diseases and colon cancer (Lit. 3,4).

In humans, activation of A1 receptors by specific A1 agonists leads to a frequency-dependent lowering of the heart rate, without any effect on blood pressure. Selective A1 agonists may thus be suitable inter alia for treating angina pectoris and atrial fibrillation.

The cardioprotective action of the A1 receptors in the heart may be utilized inter alia by activating these A1 receptors with specific A1 agonists for treatment and organ protection in cases of acute myocardial infarction, acute coronary syndrome, heart failure, bypass operations, heart catheter examinations and organ transplantations.

For the adenosine A1 receptor several subtype specific agonists have been reported like NNC-21-0126, GR79236, selodenoson and capadenoson which have been reported to be in clinical development (Lit. 5). Also the effect of adenosine A1 receptor agonists on intraocular pressure has been intensively studied and characterized. It was shown that two relatively selective adenosine A1 agonists N6-cyclohexyl-adenosine (CHA) and R(−)-N-6-(2-phenylisopropyl)adenosine (R-PIA) lower intraocular pressure in rabbits (Lit. 6,7,8) and cynomolgus monkeys (Lit. 9). However the use of adenosine A1 agonists as therapeutic drugs for glaucoma or ocular hypertension is significantly limited by the effects on hemodynamic parameters as it is known that adenosine A1 agonists are crucially involved in heart rate and blood pressure regulation (Lit. 10).

Substituted 3,5-dicyano-4-phenylpyridines and their prodrugs as potent and selective adenosine A1 agonists are disclosed in WO 03/53441, WO 2009/015776, WO 2009/015811, WO 2009/015812, WO 2010/072314, WO 2010/072315 and WO 2010/086101.

The object of the present invention is to provide an effective therapeutic agent for the treatment and/or prophalxis of glaucoma and/or ocular hypertension without showing the above mentioned side effects.

Surprisingly, it has now been found that the dicyanopyridines of formula (I) lower intraocular pressure without effecting hemodynamics and are thus suitable for the production of medicaments for the treatment and/or prophylaxis of glaucoma and ocular hypertension.

The present invention relates to compounds of formula (I)

in which A is oxygen or sulfur, R¹ is hydrogen or a group of the formula

in which

-   -   # is the attachment to the oxygen-atom,     -   L¹ is linear (C₂-C₄)-alkanediyl,     -   L² is linear (C₁-C₃)-alkanediyl,     -   R⁵ and R⁸ are identical or different and independently selected         from the group consisting of hydrogen or a a side group of a         natural α-amino acid or its homologues or isomers,     -   R⁶ and R⁹ are independently selected from hydrogen or methyl,     -   R⁷ is hydrogen or (C₁-C₄)-alkyl, or     -   R⁷ and R⁸ form together with the atoms which they are attached         to a pyrrolidine- or piperidine-ring,     -   R¹⁰ and R¹¹ are identical or different and are independently         selected from hydrogen or         -   wherein (C₁-C₄)-alkyl may be substituted with one group             selected from hydroxy, (C₁-C₄)-alkoxy, amino,             mono-(C₁-C₄)-alkylamino or di-(C₁-C₄)-alkylamino, or     -   R¹⁰ and R⁸ form together with the atoms which they are attached         to a pyrrolidine- or piperidine-ring, and     -   R¹² is hydrogen or hydroxycarbonyl,         R² is hydrogen or a group of the formula —CH₂OR¹,

wherein R¹ is defined as above,

R³ is hydrogen, methyl or ethyl, R⁴ is hydrogen, methyl or ethyl, or R³ and R⁴ form together with the nitrogen-atom, which they are bound to, a azetidine-pyrrolidine- or piperidine-ring,

-   -   wherein the azetidine-pyrrolidine- or piperidine-ring may be         substituted with one or 2 substituents independently selected         from the group fluoro, trifluoromethyl, methyl, ethyl, methoxy         and ethoxy,         and its salts, solvates and solvates of the salts,         for the use in a method treatment and/or prophylaxis of         glaucoma, normotensive glaucoma, ocular hypertension and/or         combinations thereof.

In a preferred embodiment the present invention relates to compounds of formula (I), in which

A is sulfur, R¹ is a group of the formula

in which

-   -   # is the attachment to the oxygen-atom,     -   L¹ is ethane-1,2-diyl,     -   R⁵ is hydrogen, methyl, propane-2-yl, 1-methylpropane-1-yl,         2-methylpropane-1-yl, hydroxymethyl or 1-hydroxymethyl,     -   R⁶ is hydrogen,     -   R⁷ is hydrogen,     -   R⁸ is hydrogen, methyl, propan-2-yl, 1-methylpropan-1-yl,         2-methylpropan-1-yl, imidazol-4-ylmethyl, hydroxymethyl,         hydroxyethyl, 2-carboxyethyl, 4-aminobutan-1-yl or 2-aminoethyl,     -   R⁹ is hydrogen,     -   R¹⁰ is hydrogen,     -   R¹¹ is hydrogen, or     -   R¹⁰ and R⁸ form together with the atoms which they are attached         to a pyrrolidine-ring,         R² is hydrogen,         R³ is hydrogen,         R⁴ is hydrogen, or         R³ and R⁴ form together with the nitrogen-atom, which they are         bound to, a azetidine-pyrrolidine- or piperidine-ring,         and its salts, solvates and solvates of the salts,         for the use in a method treatment and/or prophylaxis of         glaucoma, normotensive glaucoma, ocular hypertension and/or         combinations thereof.

In a preferred embodiment the present invention also relates to compounds of formula (I), in which

A is sulfur, R¹ is a group of the formula

in which

-   -   # is the attachment to the oxygen-atom,     -   R⁵ is hydrogen, methyl, propan-2-yl, 2-methylpropan-1-yl,         benzyl, hydroxymethyl or 1-hydroxyethyl,     -   R⁶ is hydrogen,     -   R⁷ is hydrogen,     -   R⁸ is hydrogen, methyl, propan-2-yl, 1-methylpropan-1-yl,         2-methylpropan-1-yl, imidazol-4-ylmethyl, 4-aminobutan-1-yl,         2-aminoethyl, 3-aminopropan-1-yl, aminomethyl or         3-guanidinopropan-1-yl,     -   R⁹ is hydrogen,     -   R¹⁰ is hydrogen,     -   R¹¹ is hydrogen,         R² is hydrogen,         R³ is hydrogen,         R⁴ is hydrogen,         and its salts, solvates and solvates of the salts,         for the use in a method treatment and/or prophylaxis of         glaucoma, normotensive glaucoma, ocular hypertension and/or         combinations thereof.

In a preferred embodiment the present invention relates to a compound of the formula (I) selected from:

-   2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]-phenoxy}ethyl-L-lysyl-D-alaninate-Dihydrochloride, -   2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]-phenoxy}ethyl-L-arginyl-D-alaninate-Dihydrochloride, -   2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]-phenoxy}ethyl-L-lysyl-D-valinate-Dihydrochloride, -   2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]-phenoxy}ethyl-L-arginyl-D-valinate-Dihydrochloride, -   2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]-phenoxy}ethyl-L-lysyl-D-phenylalaninate-Dihydrochloride, -   2-{4-[2-(Azetidin-1-yl)-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]phenoxy}ethyl-beta-alaninate-Trifluoroacetate, -   2-{4-[2-(Azetidin-1-yl)-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-ornithinate-Bis(trifluoroacetate), -   2-{4-[2-(Azetidin-1-yl)-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-lysyl-L-alaninate-Bis(trifluoroacetate), -   2-{4-[2-({[2-(4-Chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyano-6-(pyrrolidin-1-yl)pyridin-4-yl]phenoxy}ethyl-L-alanyl-L-alaninate-Hydrochloride, -   2-{4-[2-({[2-(4-Chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyano-6-(pyrrolidin-1-yl)pyridin-4-yl]phenoxy}ethyl-L-isoleucyl-L-alaninate-Hydrochloride, -   2-{4-[2-({[2-(4-Chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyano-6-(pyrrolidin-1-yl)pyridin-4-yl]phenoxy}ethyl-glycyl-L-leucinate-Hydrochloride,     for the use in a method treatment and/or prophylaxis of glaucoma,     normotensive glaucoma, ocular hypertension and/or combinations     thereof.

In a preferred embodiment the present invention also relates to compounds of formula (I), in which

R³ is hydrogen, R⁴ is hydrogen, and its salts, solvates and solvates of the salts, for the use in a method treatment and/or prophylaxis of glaucoma, normotensive glaucoma, ocular hypertension and/or combinations thereof.

In a preferred embodiment the present invention also relates to compounds of formula (I), in which

R³ and R⁴ form together with the nitrogen-atom, which they are bound to, a azetidine-pyrrolidine- or piperidine-ring, and its salts, solvates and solvates of the salts, for the use in a method treatment and/or prophylaxis of glaucoma, normotensive glaucoma, ocular hypertension and/or combinations thereof.

The compounds of formula (I), their production and their action as potent and selective adenosine A1 agonists are disclosed in WO 03/53441, WO 2009/015776, WO 2009/015811, WO 2009/015812, WO 2010/072314, WO 2010/072315 and WO 2010/086101 respectively. The compounds mentioned in WO 03/53441, WO 2009/015776, WO 2009/015811, WO 2009/015812, WO 2010/072314, WO 2010/072315 and WO 2010/086101 in general and especially the compounds specifically are explicit part of the description of the present invention.

Depending on the substitution pattern, the compounds of the formula (I) can exist in stereoisomeric forms, which behave either as image and mirror image (enantiomers) or which do not behave as image and mirror image (diastereomers). The invention relates both to the use of the enantiomers or diastereomers and to their respective mixtures. Just like the diastereomers, the racemic forms can be separated into the stereoisomerically uniform constituents in a known manner Equally, the present invention also relates to the use of the other tautomers of the compounds of the formula (I) and their salts.

Salts of the compounds of the formula (I) can be physiologically acceptable salts of the substances according to the invention with mineral acids, carboxylic acids or sulfonic acids. Particularly preferred salts are, for example, those with hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, methanesulfonic acid, ethanesulfonic acid, toluenesulfonic acid, benzenesulfonic acid, naphthalenedisulfonic acid, trifluoroacetic acid, acetic acid, propionic acid, lactic acid, tartaric acid, citric acid, fumaric acid, maleic acid or benzoic acid.

The compounds of the present invention appear preferably as hydrochlorides or trifluoroacetates.

Salts which can be mentioned are also salts with customary bases, such as, for example, alkali metal salts (e.g. sodium or potassium salts), alkaline earth metal salts (e.g. calcium or magnesium salts) or ammonium salts, derived from ammonia or organic amines such as, for example, diethylamine, triethylamine, ethyldiisopropylamine, procaine, dibenzylamine, N-methylmorpholine, dihydro-abietylamine, 1-ephenamine or methylpiperidine.

Hydrates or solvates are designated according to the invention as those forms of the compounds of the formula (I) which in the solid or liquid state form a molecular compound or a complex by hydration with water or coordination with solvent molecules. Examples of hydrates are sesqui-hydrates, monohydrates, dihydrates or trihydrates. Equally, the hydrates or solvates of salts of the compounds according to the invention are also suitable.

In the context of the present invention, the substituents, unless stated otherwise, have the following meaning:

Alkyl is in the context of the invention a straight-chain or branched alkyl radical having 1 to 4 carbon atoms. The following radicals may be mentioned by way of example and by way of preference: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl. Alkanediyl is in the context of the invention a straight-chain or branched divalent alkyl radical having 1 to 4 carbon atoms. Examples which may be preferably mentioned are: ethane-1,2-diyl (1,2-ethylene), ethane-1,1-diyl, propane-1,3-diyl (1,3-propylene), propane-1,1-diyl, propane-1,2-diyl, propane-2,2-diyl, butane-1,4-diyl (1,4-butylene), butane-1,2-diyl, butane-1,3-diyl, butane-2,3-diyl. Alkoxy is in the context of the invention a straight-chain or branched alkoxy radical having 1 to 4 carbon atoms. The following radicals may be mentioned by way of example and by way of preference: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy and tert-butoxy. Mono- or di-(C₁-C₄)-alkylamino is in the context of the invention an amino group having one or having two identical or different straight-chain or branched alkyl substituents, which in each case contain 1 to 4 carbon atoms. For example, the following may be mentioned: methylamino, ethyl-amino, n-propylamino, isopropylamino, t-butylamino, N,N-dimethylamino, N,N-diethylamino, N-ethyl-N-methylamino, N-methyl-N-n-propylamino, N-isopropyl-N-n-propylamino and N-t-butyl-N-methylamino

The side group of an α-amino acid in the meaning of R³ encompasses both the side groups of naturally occurring α-amino acids and the side groups of homologs and isomers of these α-amino acids. The α-amino acid may in this connection have both the L and the D configuration or else be a mixture of the L form and D form. Examples of side groups which may be mentioned are: methyl (alanine), propan-2-yl (valine), propan-1-yl (norvaline), 2-methylpropan-1-yl (leucine), 1-methylpropan-1-yl (isoleucine), butan-1-yl (norleucine), tert-butyl (2-tert-butylglycine), phenyl (2-phenylglycine), benzyl (phenylalanine), p-hydroxybenzyl (tyrosine), indol-3-ylmethyl (tryptophan), imidazol-4-ylmethyl (histidine), hydroxymethyl (serine), 2-hydroxyethyl (homoserine), 1-hydroxyethyl (threonine), mercaptomethyl (cysteine), methylthiomethyl (S-methylcysteine), 2-mercaptoethyl (homocysteine), 2-methylthioethyl (methionine), carbamoylmethyl (asparagine), 2-carbamoylethyl (glutamine), carboxymethyl (aspartic acid), 2-carboxyethyl (glutamic acid), 4-aminobutan-1-yl (lysine), 4-amino-3-hydroxybutan-1-yl (hydroxylysine), 3-aminopropan-1-yl (ornithine), 2-aminoethyl (2,4-diaminobutyric acid), aminomethyl (2,3-diaminopropionic acid), 3-guanidinopropan-1-yl (arginine), 3-ureidopropan-1-yl (citrulline). Preferred α-amino acid side groups in the meaning of R³ are methyl (alanine), propan-2-yl (valine), 2-methylpropan-1-yl (leucine), benzyl (phenylalanine), imidazol-4-ylmethyl (histidine), hydroxymethyl (serine), 1-hydroxyethyl (threonine), 4-aminobutan-1-yl (lysine), 3-aminopropan-1-yl (ornithine), 2-aminoethyl (2,4-diaminobutyric acid), aminomethyl (2,3-diaminopropionic acid), 3-guanidinopropan-1-yl (arginine). The L configuration is preferred in each case.

The present invention relates to selective adenosine A1 agonists, in particular the dicyanopyridines of formula (I), for the use in a method for the treatment and/or prophylaxis of glaucoma, normotensive glaucoma, ocular hypertension and/or combinations thereof.

The compounds of formula (I) act as selective adenosine A1 agonists and show a beneficial profile when administered topically to the eye, and are thus useful as an effective therapeutic agent for the treatment and/or prophylaxis of glaucoma and/or ocular hypertension.

The present invention relates to compounds of formula (I) for the use in a method for the treatment and/or prophylaxis of glaucoma and/or ocular hypertension.

Furthermore the present invention relates to compounds of formula (I) for the use in a method for the treatment and/or prophylaxis of high IOP resulting from traumatic hyphema, orbital edema, postoperative visco-elastic retention, intraocular inflammation, corticosteroid use, pupillary block, or idiopathic causes.

In addition the compounds of formula (I) are useful for the treatment and/or prophylaxis of various ocular hypertensive conditions, such as post-surgical and post-laser trabeculectomy ocular hypertensive episodes and as presurgical adjuncts.

The present invention further relates to a method of treating glaucoma, or other disease or disorder of the eye related to elevated intraocular pressure.

The present invention further relates to the use of compounds of formula (I) for the manufacture of medicaments for the treatment and/or prophylaxis of glaucoma and/or ocular hypertension.

A further subject of the present invention is a pharmaceutical composition comprising a compound of the formula (I).

A further subject of the present invention is the use of a combination of one or more compounds of the formula (I) with one or more other active compounds in a method for the treatment and/or prophylaxis of glaucoma, high IOP resulting from traumatic hyphema, orbital edema, postoperative visco-elastic retention, intraocular inflammation, corticosteroid use, pupillary block, or idiopathic causes. Examples of suitable combination active ingredients may for example and preferably be mentioned:

-   -   alpha adrenergic agonist such as for example alphagan; iopidin,         isoglaucon, catapres, aruclonin     -   beta blocker such as for example timolol, timoptol, optimal,         carteolol, ocupress, betoptic, betagan     -   carbonic anhydrase inhibitor such as for example dorzolamide,         trusopt, diamox, Acetazolamid, brinzolamid, dorzolamid,         dichlorphenamid, methazolamid.

Further disclosed herein is a method for the treatment and/or prophylaxis of high IOP, including glaucoma, ocular hypertension, normotensive glaucoma or a combination thereof comprising administering an effective amount at least one compound of formula (I) or of a medicament comprising at least one compound of formula (I) in combination with an inert, non-toxic, pharmaceutically suitable excipent to the eye.

Preferred administration route is topical administration to the eye.

Topical preparations of the invention include solutions, sprays, lotions, gels, creams, powders, powder sprays, pastes, emulsions, foams and sticks which comprise the active ingredient of the formula (I), where appropriate also a plurality of active ingredients.

Suitable pharmaceutically-acceptable carriers for topical application include those suited for use in lotions, creams, gels, solutions, ointments, viscous solutions, eye drops, emulsions, gel-forming solutions and the like.

The topically applicable preparations of the invention comprise 0.1 to 99%, preferably 0.5 to 20% by weight of active ingredient of the formula (I).

Ointments comprise hydrocarbon gels, lipogels, absorption bases, W/O ointment bases, mixed emulsions or polyethylene glycols as base.

Gels comprise solvents such as water, ethanol, isopropanol or propylene glycol and are produced using gel formers such as cellulose ethers, alginates, polyacrylates, bentonite, gelatin, tragacanth, polyvinylpyrrolidone or polyvinyl alcohol. Lipophilic gel bases or microemulsions can also be used.

Advantageously, the composition is sterile and can be in dosage unit form, e.g., suitable for topical ocular use. The composition can be packaged in a form suitable for metered application, such as in container equipped with a dropper.

In a preferred embodiment, the composition is a solution prepared using a physiological saline solution as a carrier. The pH of the solution is, preferably, maintained between 4.5 and 8.0 using an appropriate buffer system. A neutral pH is more preferred. Compositions of the invention can also comprise pharmaceutically acceptable preservatives, stabilizers and/or surfactants.

For this purpose, the active compounds can be converted into the customary preparations in a manner known per se. This takes place using inert, nontoxic, pharmaceutically suitable carriers, excipients, solvents, vehicles, emulsifiers and/or dispersants.

Suitable excipients which may be mentioned are, for example: water, nontoxic organic solvents such as, for example, paraffins, vegetable oils (e.g. sesame oil), alcohols (e.g. ethanol, glycerol), glycols (e.g. polyethylene glycol), solid carriers such as natural or synthetic ground minerals (e.g. talc or silicates), sugars (e.g. lactose), emulsifiers, dispersants (e.g. polyvinylpyrrolidone) and glidants (e.g. magnesium sulfate).

EXAMPLES

TABLE 1

Example R¹ R³ R⁴ HA 1

H H 2 HCl 2

H H 2 HCl 3

H H 2 HCl 4

H H 2 HCl 5

H H 2 HCl

The synthesis of examples 1 to 5 and corresponding starting materials is described in WO 2009/015811 in detail.

TABLE 2 Example R¹ —NR³R⁴ HA 6

CF₃CO₂H 7

CF₃CO₂H 8

CF₃CO₂H 9

HCl 10

HCl 11

HCl *is the attachment to the dicyanopyridine

The synthesis of examples 6 to 11 and corresponding starting materials is described in WO 2010/086101 in detail.

B. Experimental Methods

Advantageous pharmacological properties of the compounds which can be used according to the invention can be ascertained by the following methods.

B-1. IOP Measurements in Rats

Wistar rats with a body weight of about 300 g were anesthetized with isoflurane (2-3% in O₂:N₂O=1:2). The test compounds were diluted in 0.9% sodium chloride and given by topical administration to the eye in 10 μl volume at a concentration of 10 mg/ml. IOP was measured with a rebound tonometer (TonoLab) at different time points after application of the drugs. Ocular pressure and effects of hemodynamic parameters can be monitored in this model.

FIG. 1 shows IOP of N⁶-Cyclopentyl-Adenosine and Example 1 at a dose of 10 mg/ml.

FIG. 2 shows effects of N⁶-Cyclopentyl-Adenosine and Example 1 at a dose of 10 mg/ml on mean arterial blood pressure.

N⁶-Cyclopentyl-Adenosine and Example 1 reduce IOP at a volume of 10 μl (concentration 10 mg/ml). Surprisingly, Example 1 shows no effect on hemodynamic parameters at 10 mg/ml. However N⁶-Cyclopentyl-Adenosine significantly reduces blood pressure (FIG. 2).

B-2. Blood Pressure Measurement in Telemetric Rats

Normotensive wistar rats with a body weight of 300 to 350 g were used for this experimental study. Blood pressure was monitored in freely moving conscious animals by radiotelemetry. Briefly, the telemetric system (DSI Data Science International, MN, USA) is composed on 3 basic elements: implantable transmitters (TAUPA-C40), receivers (RA1010) and a computer-based acquisition software (Dataquest A.R.T 2.1 for Windows). Rats were instrumented with pressure implants for chronic use at least 14 days prior the experiments. Rats were anesthetized with isoflurane (2-3% in O₂:N₂O=1:2). During catheter implantation under anesthesia, rats were kept on a heating mat. A fluid-filled sensor catheter was inserted upstream into the exposed descending aorta between the iliac bifurcation and the renal arteries. According to the DSI guidelines the tip of the telemetric catheter was located just caudal to the renal arteries and secured by tissue adhesive. The transmitter body was affixed to the inner peritoneal wall before closure of abdomen. In a hardware configuration equipped for 24 animals, each rat cage was positioned on top of an individual receiver platform. After activation of the implanted transmitters, A.R.T., an on-line data acquisition system, samples data and converts telemetric pressure signals into mm Hg. Given are % deviations from the control run-in period of 2 hours before substance administration.

B-3. Nerve Crush Model

Mice (all at least 7 weeks old) were deeply anesthetized, and optic nerves were intraorbitally crushed. After treating the mice for two weeks with compounds, i.e. the adenosine A1 agonists they were sacrificed and eyes were withdrawn. Flatmounts of the retinas were prepared. The degenerated retinal ganglion cells were analyzed and counted in the different treatment groups.

B-4. Retinal Ischemia Model

Male Lewis rats weighing 200 to 250 g and male C57BL/6J mice weighing 25 to 30 g were anesthetized. The anterior chamber of one eye was cannulated with a needle attached to a line infusing normal saline to increase intraocular pressure. IOP was measured by a handheld tonometer (TonoLab) in rat eyes for the next up to 120 minutes. The other eye of the same animal was set up as a control. After ischemia, the needle was withdrawn, IOP was normalized, and reflow of the retinal circulation was documented visually. Animals were killed at different times after I/R injury. 

1. A compound of formula (I)

in which A is oxygen or sulfur, R¹ is hydrogen or a group of the formula

in which # is the attachment to the oxygen-atom, L¹ is linear (C₂-C₄)-alkanediyl, L² is linear (C₁-C₃)-alkanediyl, R⁵ and R⁸ are identical or different and independently selected from the group consisting of hydrogen or a side group of a natural α-amino acid or its homologues or isomers, R⁶ and R⁹ are independently selected from hydrogen or methyl, R⁷ is hydrogen or (C₁-C₄)-alkyl, or R⁷ and R⁵ form together with the atoms which they are attached to a pyrrolidine- or piperidine-ring, R¹⁰ and R¹¹ are identical or different and are independently selected from hydrogen or (C₁-C₄)-alkyl, wherein (C₁-C₄)-alkyl may be substituted with one group selected from hydroxy, (C₁-C₄)-alkoxy, amino, mono-(C₁-C₄)-alkylamino or di-(C₁-C₄)-alkylamino, or R¹⁰ and R⁸ form together with the atoms which they are attached to a pyrrolidine- or piperidine-ring, and R¹² is hydrogen or hydroxycarbonyl, R² is hydrogen or a group of the formula —CH₂OR¹, wherein R¹ is defined as above, R³ is hydrogen, methyl or ethyl, R⁴ is hydrogen, methyl or ethyl, or R³ and R⁴ form together with the nitrogen-atom, which they are bound to, a azetidine-, pyrrolidine- or piperidine-ring, wherein the azetidine-, pyrrolidine- or piperidine-ring may be substituted with one or 2 substituents independently selected from the group fluoro, trifluoromethyl, methyl, ethyl, methoxy and ethoxy, and the salts thereof.
 2. The compound of claim 1, wherein A is sulfur, R¹ is a group of the formula

in which # is the attachment to the oxygen-atom, L¹ is ethane-1,2-diyl, R⁵ is hydrogen, methyl, propane-2-yl, 1-methylpropane-1-yl, 2-methyl-propane-1-yl, hydroxymethyl or 1-hydroxymethyl, R⁶ is hydrogen, R⁷ is hydrogen, R⁸ is hydrogen, methyl, propan-2-yl, 1-methylpropan-1-yl, 2-methyl-propan-1-yl, imidazol-4-ylmethyl, hydroxymethyl, hydroxyethyl, 2-carboxyethyl, 4-aminobutan-1-yl or 2-aminoethyl, R⁹ is hydrogen, R¹⁰ is hydrogen, R¹¹ is hydrogen, or R¹⁰ and R⁸ form together with the atoms which they are attached to a pyrrolidine-ring, R² is hydrogen R³ is hydrogen, R⁴ is hydrogen, or R³ and R⁴ form together with the nitrogen-atom, which they are bound to, a azetidine-pyrrolidine- or piperidine-ring, and the salts thereof.
 3. The compound of claim 1, wherein A is sulfur, R¹ is a group of the formula

in which # is the attachment to the oxygen-atom, R⁵ is hydrogen, methyl, propan-2-yl, 2-methylpropan-1-yl, benzyl, hydroxy-methyl or 1-hydroxyethyl, R⁶ is hydrogen, R⁷ is hydrogen, R⁸ is hydrogen, methyl, propan-2-yl, 1-methylpropan-1-yl, 2-methyl-propan-1-yl, imidazol-4-ylmethyl, 4-aminobutan-1-yl, 2-amino ethyl, 3-aminopropan-1-yl, aminomethyl or 3-guanidinopropan-1-yl, R⁹ is hydrogen, R¹⁰ is hydrogen, R¹¹ is hydrogen, R² is hydrogen, R³ is hydrogen, R⁴ is hydrogen, and the salts thereof.
 4. The compound of claim 1, selected from the group consisting of: 2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-lysyl-D-alaninate-Dihydrochloride, 2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-arginyl-D-alaninate-Dihydrochloride, 2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-lysyl-D-valinate-Dihydrochloride, 2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-arginyl-D-valinate-Dihydrochloride, 2-{4-[2-Amino-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-lysyl-D-phenylalaninate-Dihydrochloride, 2-{4-[2-(Azetidin-1-yl)-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl) -3,5-dicyanopyridin-4-yl]phenoxy}ethyl-beta-alaninate-Trifluoroacetate, 2-{4-[2-(Azetidin-1-yl)-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl) -3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-ornithinate-Bis(trifluoroacetate), 2-{4-[2-(Azetidin-1-yl)-6-({[2-(4-chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl) -3,5-dicyanopyridin-4-yl]phenoxy}ethyl-L-lysyl-L-alaninate-Bis(trifluoroacetate), 2-{4-[2-({[2-(4-Chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyano-6-(pyrrolidin-1-yl)pyridin-4-yl]phenoxy}ethyl-L-alanyl-L-alaninate-Hydrochloride, 2-{4-[2-({[2-(4-Chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyano-6-(pyrrolidin-1-yl)pyridin-4-yl]phenoxy}ethyl-L-isoleucyl-L-alaninate-Hydrochloride, and 2-{4-[2-({[2-(4-Chlorophenyl)-1,3-thiazol-4-yl]methyl}sulfanyl)-3,5-dicyano-6-(pyrrolidin-1-yl)pyridin-4-yl]phenoxy}ethyl-glycyl-L-leucinate-Hydrochloride, and the salts thereof.
 5. (canceled)
 6. A method for the treatment of glaucoma and ocular hypertension in humans and animals by administering a therapeutically effective amount of at least one compound according to claim 1 or a medicament comprising at least one compound according to claim 1 in combination with a inert, non-toxic, pharmaceutically acceptable additive.
 7. A method for the treatment of glaucoma and ocular hypertension in humans and animals by administering topically a therapeutically effective amount of at least one compound according to claim 1 or a medicament comprising at least one compound according to claim 1 in combination with a inert, non-toxic, pharmaceutically acceptable additive. 